1. Field of the Invention
The present invention relates to apparatus for holding railroad spikes while they are being mechanically driven into a railroad tie and more particularly, to apparatus for holding railroad spikes while they are being driven by impact-type spike drivers.
2. Description of the Prior Art
In the construction of railroad tracks, rails rest on tie plates which in turn rest on wooden ties. The ties are oriented transversely to the track and are laid in ballast of various types. Tie plates consist of rectangular metal plates which generally have eight holes through which spikes may be driven into the tie. The plates are positioned over the tie and underneath each rail such that four of the holes for spikes are on each side of the rail. The holes closest to the rail are for spikes which hold the rails to the proper gauge. These are referred to as line spikes. The other holes in the tie plates are located further from the base of the rail and are for spikes which can further anchor the tie plate to the tie. These are referred to as anchor spikes.
In order to hold the rail against longitudinal movement, rail anchors are also frequently provided. Rail anchors come in various forms. These consist of a clip-like piece of metal which fits tightly around the base of the rail. In most forms, a portion of the rail anchor projects upward from the outer edge of the base of the rail and inward toward the web of the rail. The rail anchors are fitted onto the rail immediately adjacent to the ties so that the rail cannot move longitudinally relative to the tie.
The process of laying rail and then spiking that rail to gauge has seen many advances over the years. Principally, these developments have come in the form of track mounted machines designed to automate the process of driving spikes, either in the context of laying down completely new rail or in the context of replacing some or all of the ties in a particular section of track.
Among the most successful of these machines is the one disclosed in U.S. Pat. No. 4,273,052. This machine provides for rapid and accurate driving of spikes in both new and replacement/repair operations. Machines having other arrangements, by way of example, are shown in U.S. Pat. Nos. 4,131,067; 3,717,101; 3,257,962 and 3,120,195.
Common to these machines is a mechanism for holding a spike in a substantially upright position just before and while it is being driven into the tie. In U.S. Pat. No. 4,273,052, the spike is held by a pair of jaws which rotatably depend from a support member. One jaw rotates in a plane parallel to the rail and the other rotates in the plane which is at an angle of approximately 45 degrees from the vertical plane of the rail. The jaws are rotated into holding relationship with the spike by pneumatic cylinders and are rotated away from the spike by springs which take over when the pneumatic cylinders are deenergized.
In U.S. Pat. No. 4,131,067, the spike is held by a magnetic holder in connection with a channel-like device. U.S. Pat. No. 3,717,101 discloses a spike holder consisting of a pair of jaws which rotate toward one another in a horizontal plane and grip the spike pincher-like from the side. U.S. Pat. No. 3,257,962 also shows a magnetic spike holder which is attached to a spike driving hammer. U.S. Pat. No. 3,120,195 shows a pronged holder designed to carry a spike between two fork-like prongs to a vertically displaced magnetic plate which then steadies the spike in a vertical orientation preparatory to its being struck by a hammer.
In the laying of new rail, there has been a trend in the railroad industry in recent years to install rail anchors to the rail base as the rail is being laid and before it is line-spiked. This is in part a result of the substantially increased use of continuous welded rail (CWR) and the need to hold such rail against longitudinal movement. Longitudinal movement of such rail can occur because of expansion or contraction due to temperature changes or other reasons. These factors arise both during the rail laying process and after the CWR has been fully laid and spiked. It has therefore become increasingly common for rail anchors to be applied to the rail before line spiking.
Further, there has been a trend in the railroad industry toward use of impact-type spike drivers. This trend has occurred in part because impact-type spike drivers can be used more advantageously with used spikes which are often bent from prior service. Impact-type spike drivers have the further advantage of being able to fully drive a spike into a tie without the need to have the machine to which the spike driver is attached anchored to the rail by rail grippers as is shown and claimed in U.S. Patent No. 4,273,052.
As a result of these trends, there is a need for an apparatus which will hold spikes while they are being driven into the tie and which will not interfere with or dislodge the rail anchors which are already in place. These trends have also led to a need for a spike holder which can grip spikes firmly while they are being sequentially impacted by an impact-type spike driver until inserted into the tie at least a sufficient distance to permit complete driving of the spike. It is also important for such a spike holder to be able to firmly hold onto spikes even if they are hammered before the spike chisel is inserted into the appropriate hole in the tie plate and to firmly grip spikes which are bent or otherwise of slightly non-standard cross-section. Prior art devices are unable to meet these needs. In most of the prior art devices, the mechanism by which the spikes are held is either of insufficient strength to hold the spike while it is being hammered by an impact-type spike driver or in operation directly interferes with rail anchors in place at the time of spiking.